code.delx.au - gnu-emacs/blob - lisp/play/life.el

   1 ;; Conway's `Life' for GNU Emacs
   2 ;; Copyright (C) 1988 Free Software Foundation, Inc.
   3 ;; Contributed by Kyle Jones, talos!kjones@uunet.uu.net
   4
   5 ;; This file is part of GNU Emacs.
   6
   7 ;; GNU Emacs is free software; you can redistribute it and/or modify
   8 ;; it under the terms of the GNU General Public License as published by
   9 ;; the Free Software Foundation; either version 1, or (at your option)
  10 ;; any later version.
  11
  12 ;; GNU Emacs is distributed in the hope that it will be useful,
  13 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 ;; GNU General Public License for more details.
  16
  17 ;; You should have received a copy of the GNU General Public License
  18 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  19 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  20
  21 (provide 'life)
  22
  23 (defconst life-patterns
  24   [("@@@" " @@" "@@@")
  25    ("@@@ @@@" "@@  @@ " "@@@ @@@")
  26    ("@@@ @@@" "@@   @@" "@@@ @@@")
  27    ("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@")
  28    ("@@@@@@@@@@")
  29    ("   @@@@@@@@@@       "
  30     "     @@@@@@@@@@     "
  31     "       @@@@@@@@@@   "
  32     "@@@@@@@@@@          "
  33     "@@@@@@@@@@          ")
  34    ("@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@" "@")
  35    ("@               @" "@               @"  "@               @"
  36     "@               @" "@               @"  "@               @"
  37     "@               @" "@               @"  "@               @"
  38     "@               @" "@               @"  "@               @"
  39     "@               @" "@               @"  "@               @")
  40    ("@@               " " @@              " "  @@             "
  41     "   @@            " "    @@           " "     @@          "
  42     "      @@         " "       @@        " "        @@       "
  43     "         @@      " "          @@     " "           @@    "
  44     "            @@   " "             @@  " "              @@ "
  45     "               @@")
  46    ("@@@@@@@@@" "@   @   @" "@ @@@@@ @" "@ @   @ @" "@@@   @@@"
  47     "@ @   @ @" "@ @@@@@ @" "@   @   @" "@@@@@@@@@")]
  48   "Vector of rectangles containing some Life startup patterns.")
  49
  50 ;; Macros are used macros for manifest constants instead of variables
  51 ;; because the compiler will convert them to constants, which should
  52 ;; eval faster than symbols.
  53 ;;
  54 ;; The (require) wrapping forces the compiler to eval these macros at
  55 ;; compile time.  This would not be necessary if we did not use macros
  56 ;; inside of macros, which the compiler doesn't seem to check for.
  57 ;;
  58 ;; Don't change any of the life-* macro constants unless you thoroughly
  59 ;; understand the `life-grim-reaper' function.
  60 (require
  61  (progn
  62    (defmacro life-life-char () ?@)
  63    (defmacro life-death-char () (1+ (life-life-char)))
  64    (defmacro life-birth-char () 3)
  65    (defmacro life-void-char () ?\ )
  66
  67    (defmacro life-life-string () (char-to-string (life-life-char)))
  68    (defmacro life-death-string () (char-to-string (life-death-char)))
  69    (defmacro life-birth-string () (char-to-string (life-birth-char)))
  70    (defmacro life-void-string () (char-to-string (life-void-char)))
  71    (defmacro life-not-void-regexp () (concat "[^" (life-void-string) "\n]"))
  72
  73    ;; try to optimize the (goto-char (point-min)) & (goto-char (point-max))
  74    ;; idioms.  This depends on goto-char's not griping if we underrshoot
  75    ;; or overshoot beginning or end of buffer.
  76    (defmacro goto-beginning-of-buffer () '(goto-char 1))
  77    (defmacro maxint () (lsh (lsh (lognot 0) 1) -1))
  78    (defmacro goto-end-of-buffer () '(goto-char (maxint)))
  79
  80    (defmacro increment (variable) (list 'setq variable (list '1+ variable)))
  81    'life))
  82
  83 ;; list of numbers that tell how many characters to move to get to
  84 ;; each of a cell's eight neighbors.
  85 (defconst life-neighbor-deltas nil)
  86
  87 ;; window display always starts here.  Easier to deal with than
  88 ;; (scroll-up) and (scroll-down) when trying to center the display.
  89 (defconst life-window-start nil)
  90
  91 ;; For mode line
  92 (defconst life-current-generation nil)
  93 ;; Sadly, mode-line-format won't display numbers.
  94 (defconst life-generation-string nil)
  95
  96 (defun abs (n) (if (< n 0) (- n) n))
  97
  98 (defun life (&optional sleeptime)
  99   "Run Conway's Life simulation.
 100 The starting pattern is randomly selected.  Prefix arg (optional first
 101 arg non-nil from a program) is the number of seconds to sleep between
 102 generations (this defaults to 1)."
 103   (interactive "p")
 104   (or sleeptime (setq sleeptime 1))
 105   (life-setup)
 106   (life-display-generation sleeptime)
 107   (while t
 108     (let ((inhibit-quit t))
 109       (life-grim-reaper)
 110       (life-expand-plane-if-needed)
 111       (life-increment-generation)
 112       (life-display-generation sleeptime))))
 113
 114 (fset 'life-mode 'life)
 115 (put 'life-mode 'mode-class 'special)
 116
 117 (random t)
 118
 119 (defun life-setup ()
 120   (let (n)
 121     (switch-to-buffer (get-buffer-create "*Life*") t)
 122     (erase-buffer)
 123     (kill-all-local-variables)
 124     (setq case-fold-search nil
 125           mode-name "Life"
 126           major-mode 'life-mode
 127           truncate-lines t
 128           life-current-generation 0
 129           life-generation-string "0"
 130           mode-line-buffer-identification '("Life: generation "
 131                                             life-generation-string)
 132           fill-column (1- (window-width))
 133           life-window-start 1)
 134     (buffer-disable-undo (current-buffer))
 135     ;; stuff in the random pattern
 136     (life-insert-random-pattern)
 137     ;; make sure (life-life-char) is used throughout
 138     (goto-beginning-of-buffer)
 139     (while (re-search-forward (life-not-void-regexp) nil t)
 140       (replace-match (life-life-string) t t))
 141     ;; center the pattern horizontally
 142     (goto-beginning-of-buffer)
 143     (setq n (/ (- fill-column (save-excursion (end-of-line) (point))) 2))
 144     (while (not (eobp))
 145       (indent-to n)
 146       (forward-line))
 147     ;; center the pattern vertically
 148     (setq n (/ (- (1- (window-height))
 149                   (count-lines (point-min) (point-max)))
 150                2))
 151     (goto-beginning-of-buffer)
 152     (newline n)
 153     (goto-end-of-buffer)
 154     (newline n)
 155     ;; pad lines out to fill-column
 156     (goto-beginning-of-buffer)
 157     (while (not (eobp))
 158       (end-of-line)
 159       (indent-to fill-column)
 160       (move-to-column fill-column)
 161       (delete-region (point) (progn (end-of-line) (point)))
 162       (forward-line))
 163     ;; expand tabs to spaces
 164     (untabify (point-min) (point-max))
 165     ;; before starting be sure the automaton has room to grow
 166     (life-expand-plane-if-needed)
 167     ;; compute initial neighbor deltas
 168     (life-compute-neighbor-deltas)))
 169
 170 (defun life-compute-neighbor-deltas ()
 171   (setq life-neighbor-deltas
 172         (list -1 (- fill-column)
 173               (- (1+ fill-column)) (- (+ 2 fill-column))
 174               1 fill-column (1+ fill-column)
 175               (+ 2 fill-column))))
 176
 177 (defun life-insert-random-pattern ()
 178   (insert-rectangle
 179    (elt life-patterns (% (abs (random)) (length life-patterns))))
 180   (insert ?\n))
 181
 182 (defun life-increment-generation ()
 183   (increment life-current-generation)
 184   (setq life-generation-string (int-to-string life-current-generation)))
 185
 186 (defun life-grim-reaper ()
 187   ;; Clear the match information.  Later we check to see if it
 188   ;; is still clear, if so then all the cells have died.
 189   (store-match-data nil)
 190   (goto-beginning-of-buffer)
 191   ;; For speed declare all local variable outside the loop.
 192   (let (point char pivot living-neighbors list)
 193     (while (search-forward (life-life-string) nil t)
 194       (setq list life-neighbor-deltas
 195             living-neighbors 0
 196             pivot (1- (point)))
 197       (while list
 198         (setq point (+ pivot (car list))
 199               char (char-after point))
 200         (cond ((eq char (life-void-char))
 201                (subst-char-in-region point (1+ point)
 202                                      (life-void-char) 1 t))
 203               ((< char 3)
 204                (subst-char-in-region point (1+ point) char (1+ char) t))
 205               ((< char 9)
 206                (subst-char-in-region point (1+ point) char 9 t))
 207               ((>= char (life-life-char))
 208                (increment living-neighbors)))
 209         (setq list (cdr list)))
 210       (if (memq living-neighbors '(2 3))
 211           ()
 212         (subst-char-in-region pivot (1+ pivot)
 213                             (life-life-char) (life-death-char) t))))
 214   (if (null (match-beginning 0))
 215       (life-extinct-quit))
 216   (subst-char-in-region 1 (point-max) 9 (life-void-char) t)
 217   (subst-char-in-region 1 (point-max) 1 (life-void-char) t)
 218   (subst-char-in-region 1 (point-max) 2 (life-void-char) t)
 219   (subst-char-in-region 1 (point-max) (life-birth-char) (life-life-char) t)
 220   (subst-char-in-region 1 (point-max) (life-death-char) (life-void-char) t))
 221
 222 (defun life-expand-plane-if-needed ()
 223   (catch 'done
 224     (goto-beginning-of-buffer)
 225     (while (not (eobp))
 226       ;; check for life at beginning or end of line.  If found at
 227       ;; either end, expand at both ends,
 228       (cond ((or (eq (following-char) (life-life-char))
 229                  (eq (progn (end-of-line) (preceding-char)) (life-life-char)))
 230              (goto-beginning-of-buffer)
 231              (while (not (eobp))
 232                (insert (life-void-char))
 233                (end-of-line)
 234                (insert (life-void-char))
 235                (forward-char))
 236            (setq fill-column (+ 2 fill-column))
 237            (scroll-left 1)
 238            (life-compute-neighbor-deltas)
 239            (throw 'done t)))
 240       (forward-line)))
 241   (goto-beginning-of-buffer)
 242   ;; check for life within the first two lines of the buffer.
 243   ;; If present insert two lifeless lines at the beginning..
 244   (cond ((search-forward (life-life-string)
 245                          (+ (point) fill-column fill-column 2) t)
 246          (goto-beginning-of-buffer)
 247          (insert-char (life-void-char) fill-column)
 248          (insert ?\n)
 249          (insert-char (life-void-char) fill-column)
 250          (insert ?\n)
 251          (setq life-window-start (+ life-window-start fill-column 1))))
 252   (goto-end-of-buffer)
 253   ;; check for life within the last two lines of the buffer.
 254   ;; If present insert two lifeless lines at the end.
 255   (cond ((search-backward (life-life-string)
 256                           (- (point) fill-column fill-column 2) t)
 257          (goto-end-of-buffer)
 258          (insert-char (life-void-char) fill-column)
 259          (insert ?\n)
 260          (insert-char (life-void-char) fill-column)
 261          (insert ?\n)
 262          (setq life-window-start (+ life-window-start fill-column 1)))))
 263
 264 (defun life-display-generation (sleeptime)
 265   (goto-char life-window-start)
 266   (recenter 0)
 267   (sit-for sleeptime))
 268
 269 (defun life-extinct-quit ()
 270   (life-display-generation 0)
 271   (signal 'life-extinct nil))
 272
 273 (put 'life-extinct 'error-conditions '(life-extinct quit))
 274 (put 'life-extinct 'error-message "All life has perished")